Confusion About Using Sweep Elbows

Even amongst building officials and seasoned builders, we’re still seeing confusion about the benefits of using sweep elbows when plumbing a pool. If a plumbing system is designed properly and conforms to the maximum line velocity standards, then sweep elbows are a moot point.

The keys, are design flow rates of 4.5 FPS suction and 6 FPS return. These guarantee that once installed, the system flow rates will not exceed the code maximums of 6 FPS suction and 8 FPS returns.It is the line velocity that creates cavitation at elbows. Regardless of the pipe diameter, if the flow is kept within check, then sweeps are not required.

Slower moving water does not slam into the corner of a 90º elbow, and does not cavitate. Legislatures bought into the fallacy that sweep elbows would increase energy efficiency. They responded by mandating the use of sweep elbows, without regard to pipe diameters or line velocities. In reality, they should have mandated hydraulic calculations and line velocities.That would have required that builders use larger diameter pipes and slow the line velocities.

Builders who actually bother to design their hydraulics, are being forced to use sweep elbows (when they’re really not required). Fortunately, the energy code already mandates maximum line velocities of 6 FPS suction and 8 FPS returns. Now, all we have to do is get the sweep elbow mandate removed and educate building officials about line velocities and energy standards.

Swimming Pool Expert Witness